Please suggest food for stag horn kidney?

Q:I am a 28 years old married women. My left kidney, operated for stag horn, is presently functioning only 2 % but the right kidney is normal. How much water is appropriate to drink? I am drinking 4 ½ liters a day. Some people say this will put a load on the right kidney - is this true? What are the foods/drinks I need to have and which do I need to avoid? Any particular dos and don'ts to avoid infection or stone? Does the herb red mushroom revive the kidney function? I am planning to conceive too; is it safe for me to take folic acid?

A:Perhaps the most important step you can take towards preventing kidney stones is drinking 12 full glasses of water a day. If your remaining kidney is healthy and your kidney tests are reported normal there is no need to exercise water restriction. Drinking lots of water helps to flush away the substances that form stones in the kidneys. You can also drink ginger ale, lemon-lime sodas, and fruit juices. But water is best. Having enough water in your body will help to reduce the concentration of calcium in the fluid that your kidney filters. High concentrations of calcium and oxalate, phosphate or other minerals are needed to form stones.
Another approach to preventing kidney stones in adults is to eat calcium rich foods and avoid oxalates. This works in two ways 1) reducing the amount of oxalate available, and 2) if calcium is present in the diet with oxalate, then calcium and oxalate bind in the intestine. This way, less calcium and oxalate enter the blood so that oxalates are not available to bind with calcium in the kidney. You should not use calcium supplements unless you talk to your doctor.
Very high intakes of sodium and protein may cause kidney stones. You should use little salt in cooking or at the table and avoid many high sodium processed foods. See the low-sodium diet section for more details. Most people should have 2 portions of protein foods per day. The portions should be about the size of a deck of cards or a quarter-pound hamburger after it is cooked.
High Oxalate Foods to Avoid
If you avoid the foods listed below you can reduce your oxalate intake. If you eat a large amount of foods on this list, eating less may be helpful.

Chocolate

Tea

Spinach

Beet tops

Peanuts

Almonds

Pecans
High Calcium Foods to Choose
Many other foods may be good sources of calcium, but those listed below are sources that are commonly available and many people may like to use.

Dairy Products
-For adults and children over 5

Skim or 1% milk

Low-fat yogurt

Low-fat cheeses
As far as red Reishi mushrooms go there is little scientific evidence to support its role in curing stone disease. In fact, on the contrary several mushrooms have been known to be associated with kidney failure, liver failure and at times death.
It is perfectly safe for you to take folic acid.